The invention relates to a transport unit attachable to a transport truck, such as a transport truck trailer or body, the transport unit comprising a base.
Transports units, such as trailers, are used for the road transport of most diversified goods. Since trailers are required to have a good load carrying capacity, they are equipped with multiple axles, for example five, i.e. with a two-axle front unit and a three-axle rear unit. Most trailers have three, four or five axles. Trailers are commonly used for transporting bulk goods, in which case the unit is a bulk trailer. Another known trailer type is a tank trailer. The demand for continuously enhanced operations naturally concerns the transport service as well, and therefore trailer weight and its useful height are becoming increasingly significant.
In known solutions applied in the field the trailer is provided with a separate frame onto which the trailer floor is built. The frame of the trailer also serves as an attachment for the axle group. The separate frame consists of two longitudinal beams on different sides of the trailer""s centre line and multiple transverse support beams between them. The material is common steel, also known as black steel. The longitudinal beams are I-beams, and the number of support beams required between them is high. The vertical reach of the longitudinal beams is as much as 52 cm and even at the front of the trailer it is about 12 cm, the material thickness of the beams being 8 millimeters. The structure is naturally sufficiently stiff for its purpose of use, but a separate frame inevitably increases the weight of the trailer significantly, a further disadvantage of the increased weight being that the two superimposed structures, i.e. the frame and the base, or the floor, above it together form a structure which so high that a maximal useful height cannot be obtained. As regards the prior art solution, reference is made to FIGS. 1a and 1b, which show a separate frame 41, a floor 42, a front axle group 43 and a rear axle group 44. The total length of the five-axle trailer of FIGS. 1a and 1b is about 13.6 meters. In the implementation shown in FIGS. 1a and 1b, the trailer mass without the axles is as much as about 103 kg/m2 and the total height of the construction from the bottom surface of the tires to the upper surface of the trailer base is 1276 mm. The trailer mass naturally decreases the amount of the useful load mass transportable with the trailer. The relatively low useful height of the trailer naturally reduces the capacity of the trailer, which has also a decreasing effect on the amount of useful load. The relatively low useful load capacity naturally has also financial consequences, because the amount of goods transported per time unit is smaller than when a trailer with higher useful load capacity is used. In the transport of some materials, such as peat, the magnitude of the useful load capacity is even highly critical because the transport costs have an impact on the cost effectiveness of the use of the transported material.
When the transport unit in question is a transport truck body, known implementations are basically of the same type as known transport truck trailers, i.e. there is a separate frame under the base of the body. Also the disadvantages are similar, i.e. high weight and relatively low useful height.
It is an object of the invention to provide a novel transport unit that allows the above problems to be significantly reduced.
This is achieved with a transport unit attachable to a transport truck, characterized in that the transport unit is implemented without a separate frame, the transport unit base being a compartmental, self-supporting base made of stainless steel and forming the transport unit frame.
The preferred embodiments of the invention are disclosed in the dependent claims.
The basic idea of the invention is that a specially built transport unit floor also serves as the frame of the transport unit. The floor of the transport unit, i.e. the floor of a transport truck trailer or the floor of a transport truck body is thus implemented as a compartmental self-supporting structure. When the transport unit in question is a trailer, the specially constructed floor of the trailer also forms the frame of the trailer to which the axle groups can be attached.
The transport unit of the invention provides several advantages. The most essential advantage is a significant reduction in weight, which in the case of a five-axle trailer of 13.6 meters, for example, is about 1000-1800 kg, depending on the implementation. The lower weight is possible because there is no separate frame. On one hand, the use of stainless steel provides strength and, on the other, it is lighter than a conventional steel material. Moreover, since the structure is implemented without a separate frame and a separate floor on top of it, it has been possible to make the base of the trailer lower, which significantly increases the useful height of the trailer, this increase being, according to the applicant""s observations, about 6-7 cm in an implementation of a five-axle trailer of 13.6 meters of the type described above. According to the invention, the weight per square meter obtained for the base of the above five-axle trailer of 13.6 meters is as low as 20 kg/m2, the axles being not included. Irrespective of the purpose of use of the trailer, the reduction in the trailer mass and the increase in the amount of the transportable useful mass resulting from the increased useful height provide significant financial advantages. Due to the increased useful mass the financial implications in the case of a peat trailer, for example, have already a fairly crucial impact in ensuring the economical efficiency of peat transports and, consequently, peat use. The advantages of the invention relative to the transport truck body are similar than those relative to the trailer, i.e. savings in weight and increased useful height.